PROJECT SUMMARY/ABSTRACT Being able to read braille and understand tactile graphics is crucial for people who are blind and can no longer read text and graphics visually. Braille replaces text with raised dots, and tactile graphics replace visual graphics with raised lines, textures, and elevations. Blind children, adults, and elderly persons use braille and tactile graphics to access educational and professional content, maintain independence, and participate in their local communities and society (e.g., reading the news). Being braille and tactile-graphic literate involves knowing the symbols (e.g., braille letters) and being able to use effective hand-exploration strategies to read and explore. There are many different hand-movement strategies that can be used, but there is no consensus on which hand-movement strategy is best, and if this varies depending on an individual?s age, knowledge, and skills. The proposed research will directly address which hand movements work best for an individual. During the mentored phase of the award, experiments will be conducted to identify the knowledge and skills that contribute to braille reading and tactile-graphic exploration. The relationship between knowledge/skills and hand-movement strategies will be specified using ideal observer models, which may include Bayesian search models. The models will predict the best hand-movement strategies for an individual to quickly read braille and find a target on a tactile-graphic depending on the individual?s knowledge and skills. During the independent phase of the award, ideal-observer predictions will be compared to the hand-movement strategies used by blind people. It is possible that people use the strategies best suited for their knowledge/skills, but it?s also possible that people use suboptimal strategies that they have been trained to use. Finally, training in ?good? and ?poor? strategies, with subsequent performance evaluation, will used to evaluate ideal-observer predictions. Taken together, these studies will close a gap in the understanding of hand-movement strategies for braille reading and tactile-graphic exploration. Rehabilitation providers, such as those who teach braille and tactile graphics to adults at vocational rehabilitation centers or to children as teachers of students with visual impairments, can use the results from this research to inform their braille and tactile-graphic ministration, instead of falling back on their instincts and conventions.